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|
#! /usr/env/bin ruby
#--
# Copyright 2004 Austin Ziegler <diff-lcs@halostatue.ca>
# adapted from:
# Algorithm::Diff (Perl) by Ned Konz <perl@bike-nomad.com>
# Smalltalk by Mario I. Wolczko <mario@wolczko.com>
# implements McIlroy-Hunt diff algorithm
#
# This program is free software. It may be redistributed and/or modified under
# the terms of the GPL version 2 (or later), the Perl Artistic licence, or the
# Ruby licence.
#
# $Id$
#++
# Provides Diff::LCS::Change and Diff::LCS::ContextChange.
# Centralises the change test code in Diff::LCS::Change and
# Diff::LCS::ContextChange, since it's the same for both classes.
module Diff::LCS::ChangeTypeTests
def deleting?
@action == '-'
end
def adding?
@action == '+'
end
def unchanged?
@action == '='
end
def changed?
@changed == '!'
end
def finished_a?
@changed == '>'
end
def finished_b?
@changed == '<'
end
end
# Represents a simplistic (non-contextual) change. Represents the removal or
# addition of an element from either the old or the new sequenced enumerable.
class Diff::LCS::Change
# Returns the action this Change represents. Can be '+' (#adding?), '-'
# (#deleting?), '=' (#unchanged?), # or '!' (#changed?). When created by
# Diff::LCS#diff or Diff::LCS#sdiff, it may also be '>' (#finished_a?) or
# '<' (#finished_b?).
attr_reader :action
attr_reader :position
attr_reader :element
include Comparable
def ==(other)
(self.action == other.action) and
(self.position == other.position) and
(self.element == other.element)
end
def <=>(other)
r = self.action <=> other.action
r = self.position <=> other.position if r.zero?
r = self.element <=> other.element if r.zero?
r
end
def initialize(action, position, element)
@action = action
@position = position
@element = element
end
# Creates a Change from an array produced by Change#to_a.
def to_a
[@action, @position, @element]
end
def self.from_a(arr)
Diff::LCS::Change.new(arr[0], arr[1], arr[2])
end
include Diff::LCS::ChangeTypeTests
end
# Represents a contextual change. Contains the position and values of the
# elements in the old and the new sequenced enumerables as well as the action
# taken.
class Diff::LCS::ContextChange
# Returns the action this Change represents. Can be '+' (#adding?), '-'
# (#deleting?), '=' (#unchanged?), # or '!' (#changed?). When
# created by Diff::LCS#diff or Diff::LCS#sdiff, it may also be '>'
# (#finished_a?) or '<' (#finished_b?).
attr_reader :action
attr_reader :old_position
attr_reader :old_element
attr_reader :new_position
attr_reader :new_element
include Comparable
def ==(other)
(@action == other.action) and
(@old_position == other.old_position) and
(@new_position == other.new_position) and
(@old_element == other.old_element) and
(@new_element == other.new_element)
end
def inspect(*args)
%Q(#<#{self.class.name}:#{__id__} @action=#{action} positions=#{old_position},#{new_position} elements=#{old_element.inspect},#{new_element.inspect}>)
end
def <=>(other)
r = @action <=> other.action
r = @old_position <=> other.old_position if r.zero?
r = @new_position <=> other.new_position if r.zero?
r = @old_element <=> other.old_element if r.zero?
r = @new_element <=> other.new_element if r.zero?
r
end
def initialize(action, old_position, old_element, new_position, new_element)
@action = action
@old_position = old_position
@old_element = old_element
@new_position = new_position
@new_element = new_element
end
def to_a
[@action, [@old_position, @old_element], [@new_position, @new_element]]
end
# Creates a ContextChange from an array produced by ContextChange#to_a.
def self.from_a(arr)
if arr.size == 5
Diff::LCS::ContextChange.new(arr[0], arr[1], arr[2], arr[3], arr[4])
else
Diff::LCS::ContextChange.new(arr[0], arr[1][0], arr[1][1], arr[2][0],
arr[2][1])
end
end
# Simplifies a context change for use in some diff callbacks. '<' actions
# are converted to '-' and '>' actions are converted to '+'.
def self.simplify(event)
ea = event.to_a
case ea[0]
when '-'
ea[2][1] = nil
when '<'
ea[0] = '-'
ea[2][1] = nil
when '+'
ea[1][1] = nil
when '>'
ea[0] = '+'
ea[1][1] = nil
end
Diff::LCS::ContextChange.from_a(ea)
end
include Diff::LCS::ChangeTypeTests
end
|
